Two robotic spacecraft nearing Mars were built and paid for by NASA grownups, but it was a 10-year-old girl born in a Siberian orphanage who dreamed up their inspirational names, “Spirit” and “Opportunity.” The centerpieces of an $820 million mission to explore the rugged Martian terrain, the two golf-cart-sized robotic rovers are on course to attempt landings late on Jan. 3 and Jan. 24. Now a fourth-grader in Scottsdale, Ariz., Sofi Collis submitted the winning entry in an essay contest sponsored by NASA, the Danish toy company Lego, and the Planetary Society. She beat out nearly 10,000 elementary, middle and high school contestants, who attempted to suggest names and provide an explanation in no more than 50 words.